Remotely reconfigurable high pressure fluid passive control system for controlling bi-directional piston pumps as active sources of high pressure fluid, as inactive rigid structural members or as isolated free motion devices

ABSTRACT

A bi-directional pump system that can be configured for a plurality of operating modes. The bi-directional pump system includes a plurality of bi-directional pumps each having their own valving system that are connected to a common high pressure manifold, a low pressure manifold and a suction manifold. Via the respective valve systems, each pump can be configured into: (1) a single-acting pumping mode; (2) a double-acting pumping mode; (3) an inactive free motion mode; and (4) an inactive rigid mode. One exemplary application of the bi-directional pump system is on an articulated wave energy conversion system that consists of three floating barges: a front barge, a center barge and a rear barge where the front barge and center barge are hingedly connected as are the center barge and the rear barge. A first set of the bi-directional pumps span the first hinge connection and the second set of bi-directional pumps span the second hinge connection. The bi-directional pump system intakes sea water and, using wave energy, outputs a high pressure flow of sea water for water desalination and/or for driving electrical generators.

BACKGROUND OF THE INVENTION

The present invention relates in general to high pressure pump systemsand, more particularly, to a remotely-configurable high pressure fluidpassive control system for controlling bi-directional pumps.

Richard Peter McCabe devised the McCabe Wave Pump, which is described inU.S. Pat. No. 5,132,550. The McCabe Wave Pump consists of threerectangular steel pontoons, which move relative to each other in thewaves. A damper wave plate attached to the central pontoon ensures thatit remains stationary as the fore and aft pontoons move relative to thecentral pontoon by pitching about the hinges. Energy is extracted fromthe rotation about the hinge points by linear hydraulic pumps mountedbetween the central and other two pontoons near the hinges.

A related configuration to the McCabe Wave Pump is an “articulated waveenergy conversion system (AWECS)” which is disclosed in U.S. PatentPublication Nos. 2014/0008306 (Murtha, et al.); 2014/0158624 (Murtha, etal.); and U.S. Patent Publication No. 2014/0091575 (McCormick, et al.),and all of which are owned by the same Assignee as the presentapplication, namely, Murtec, Inc. of Glen Burnie, Md. See also U.S. Pat.No. 8,650,869 (McCormick). As shown in FIG. 1, an AWECS uses a pluralityof pneumatic or hydraulic pumps P (hereinafter, “hydraulic” is used, itbeing understood that “pneumatic” is also interchangeable with“hydraulic”) that straddle the two articulating barges, a forward bargeFB and a rear barge RB which are coupled together, e.g. by hinges. Adamper wave plate (DWP) attached to a central barge CB ensures that itremains stationary as the fore FB and aft RB barges move relative to thecentral barge CB by pitching about the hinges. As an incoming wave makescontact with the forward barge FB first, the hydraulic fluid in thepumps coupled between the forward barge FB and the center barge CB aredriven in a first direction; as the wave continues, the hydraulic fluidin the pumps P coupled between the rear barge RB and the center barge CBare driven in a second opposite direction. The end results arebi-directional hydraulic pumps P. The output of these hydraulic pumps Pare used for water desalination or energy conversion.

Doug Hicks and Charles M. Pleass devised the Delbuoy wave-powereddesalination unit, described in U.S. Pat. Nos. 5,013,219; 4,512,886;4,421,461, and 4,326,840. When the waves lift and then lower the Delbuoywave-powered desalination unit, a piston connected to the bottom of thebuoy drives a piston pump at the sea floor. The pressure created by thepump is strong enough to drive the sea water through a reverse osmosisfilter, which removes salt and impurities from the water, and then tosend the fresh water through a pipe to the shoreline, where it is tappedand used by people.

However, there remains a need for quickly and easily reconfiguring theoperational modes of pumps depending on different scenarios which noneof the aforementioned disclosures teach or suggest.

All references cited herein are incorporated herein by reference intheir entireties.

BRIEF SUMMARY OF THE INVENTION

A bi-directional pump system for providing a high pressure fluid outputis disclosed. The pump system comprises: at least one bi-directionalpump having a piston and piston rod that can translate within a cylinderin two opposite directions, wherein the piston separates the cylinderinto two variable-sized chambers, and wherein the piston displaces fluidlocated in each chamber when the piston is in motion due to externalforces acting through the piston rod and the cylinder; each variablechamber being in fluid communication through a valve network to a highpressure manifold, a low pressure manifold and a suction manifold,wherein the high pressure manifold has an output for delivering the highpressure fluid to a target process and wherein the suction manifoldprovides a fluid input into the bi-directional pump system; and whereinthe valve network can be configured to deliver high pressure fluid fromone of a single-acting pumping mode and a double-acting pumping mode,wherein the single-acting pumping mode delivers high pressure fluid tothe target process during piston motion in one of the two oppositedirections and wherein the double-acting pumping mode delivers highpressure fluid to the target process during piston motion in both of thetwo opposite directions.

A method for permitting a plurality of parallel-acting bi-directionalpumps to be configured into a plurality of operational modes isdisclosed. The method comprises: providing a plurality of bi-directionalpumps, each bi-directional pump having a piston and piston rod that cantranslate within a cylinder in two opposite directions, wherein eachpiston separates the corresponding cylinder into two variable-sizedchambers, wherein the piston displaces fluid located in each chamberwhen the piston is in motion due to external forces acting through eachpiston rod and each cylinder; coupling each variable-sized chamber,through a respective valve network, to a high pressure manifold, a lowpressure manifold and a suction manifold, wherein the high pressuremanifold has an output for delivering the high pressure fluid to atarget process and wherein the suction manifold provides a fluid inputinto the bi-directional pump system; and controlling the valve networkso that each one of the plurality of bi-directional pumps can beconfigured to deliver high pressure fluid from one of a single-actingpumping mode and a double-acting pumping mode, wherein the single-actingpumping mode delivers high pressure fluid to the target process duringpiston motion in one of the two opposite directions and wherein thedouble-acting pumping mode delivers high pressure fluid to the targetprocess during piston motion in both of the two opposite directions.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the present disclosure. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is an isometric view of a prior art articulate barge wave-energyconverter system (AWECS);

FIG. 2 shows the invention of the present application integrated on anAWECS;

FIG. 3 is a block diagram of the invention, shown for the Single-ActingPumping Mode (SAPM), by way of example only, and wherein an exemplarytarget process is a reverse osmosis (RO) water desalination stage;

FIG. 4 depicts one of the high pressure pumps of the present inventionand its associated valve system for implementing the four modes of pumpcontrol while also showing the high pressure manifold, low pressuremanifold and suction manifold shared by all of the pumps;

FIG. 5A depicts the particular valve states for implementing theSingle-Acting Pumping Mode (SAPM) during the piston rod extensionhalf-cycle in one of the pumps;

FIG. 5B depicts the particular valve states for implementing the SAPMduring the piston rod retraction half-cycle in the pump of FIG. 5A;

FIG. 6A depicts the particular valve states for implementing theDouble-Acting Pumping Mode (DAPM) during the piston rod extensionhalf-cycle in one of the pumps;

FIG. 6B depicts the particular valve states for implementing the DAPMduring the piston rod retraction half-cycle in the pump of FIG. 6A;

FIG. 7A depicts the particular valve states for implementing theInactive Free Motion Mode (IFMM) during the piston rod extensionhalf-cycle in one of the pumps;

FIG. 7B depicts the particular valve states for implementing the IFMMduring the piston rod retraction half-cycle in the pump of FIG. 7A;

FIG. 8A depicts the particular valve states for implementing theInactive Rigid Mode (IRM) during the piston rod extension half-cycle inone of the pumps;

FIG. 8B depicts the particular valve states for implementing the IRMduring the piston rod retraction half-cycle in the pump of FIG. 8A;

FIG. 9A is a functional diagram of the piston, piston rod and cylinderof one of the pumps; and

FIGS. 9B-9C depict the annular volume of the rod-end of cylinder due tothe presence of the piston rod.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures, wherein like reference numerals representlike parts throughout the several views, exemplary embodiments of thepresent disclosure will be described in detail. Throughout thisdescription, various components may be identified having specificvalues, these values are provided as exemplary embodiments and shouldnot be limiting of various concepts of the present invention as manycomparable sizes and/or values may be implemented.

The present invention 20 relates in general to an apparatus comprising aliquid pipe and valve system or network designed to be configuredlocally or remotely and passively control the operation ofbi-directional piston pumps in any of four modes:

-   -   (1) Single-Acting Pumping Mode (SAPM): a single-ended piston        source of high pressure fluid only from rod end piston fluid        connection as piston rod is being extended;    -   (2) Double-Acting Pumping Mode (DAPM): a single-ended piston        source of high pressure fluid from both piston fluid connections        as piston rod is being extended and retracted;    -   (3) Inactive Free Motion Mode (IFMM): an isolated cylinder with        both piston fluid connections isolated but with them connected        to each other to permit free movement of the piston with minimum        force for isolating the cylinder from the system while the        remainder of a bank of multi-mode pumps continue to pump        pressurized fluid; and    -   (4) Inactive Rigid Mode (IRM): an isolated cylinder with both        piston fluid connections isolated to create a hydraulic lock on        the piston to provide a rigid structural member between the two        sources of force on the piston rod and housing.        As a result, the apparatus 20 has an unlimited number of uses        (hence the term “target process” used in several of the figures)        high pressure fluid is required and the need to use these four        modes operation are available. Thus, by way of example only and        not by way of limitation, as shown in FIG. 2, this apparatus 20        is depicted being implemented on an articulated wave energy        conversion system (AWECS) 10 for implementing water desalination        and/or ocean energy wave conversion. Specifically, it relates to        the exploitation of ocean wave energy in the production of        potable water by reverse osmosis desalination, or the generation        of electricity by driving an electrical generator. Ocean energy        comes in a variety of forms including tidal currents, ocean        currents, and surface waves. Wave power is the transport of        energy by surface waves, and the capture of that energy to do        useful work. Thus, the following description shows the        implementation of the apparatus 20 in an AWECS environment        simply by way of example.

FIG. 3 shows an overview of the system 20 implemented for waterdesalination (by way of example only) and during a particular mode,namely, SAPM, for clarity only. As shown, the target process utilizes aplurality of reverse osmosis (RO) tubes for desalinating the highpressure water; the output of these tubes results in a potable waterflow, as well as a brine waste flow. As can be seen, a first set of highpressure (HP) pumps (e.g., five pumps A-E, indicated as “A-E”) are thosethat straddle the FB/CB barges while the second set of HP pumps (e.g.,another five pumps “F-J”) are those that straddle the CB/RB barges. Eachpump A-J are identical and any one of them will be referred to herein as“pump 20A.” Each of the HP pumps valve systems, as discussed in detailbelow, may be automatically controlled by a processor PR that can belocated remotely or locally with respect to the pumps 20A. Moreover, thecommunication link CL between the processor and valve system may beeither a wired or wireless interface. Alternatively, each valve in thevalve system for each pump may be manually controlled by servicepersonnel, if desired.

The terms “high pressure (HP)” and “low pressure (LP)” as usedthroughout this Specification may comprise approximately 1000 psi and100 psi, respectively.

FIG. 4 depicts a single HP pump 20A (e.g., a single-ended piston pump)and how it is coupled in fluid communication with the other HP pumps inthe system 20. As can be seen, each pump 20A comprises a single rod enddouble-acting cylinder. In particular, a piston head 100 driven by apiston rod 102 is moved back and forth within the cylinder 104 which hasa non-rod end 104A and a rod end 104B. These two cylinder chambers104A/104B are in fluid communication with a high pressure (HP) manifold106, a low pressure (LP) manifold 108 and a suction manifold 110 througha network of valves, generally referred to as the HP pump's “valvesystem.” The valve system includes fluid pipes and fittings, remotelypositioned 2-way full-port ball valves that can be actuated locally orremotely (as discussed previously with regard to FIG. 3), check valves,hydraulic accumulators, pressure control/relief valves, and a separatelycontrolled back flush valve.

As mentioned previously, the piston 100 within the cylinder 104 is movedback and forth within the cylinder 104 by the motion of alternatelyextending and retracting the connected piston rod 102 relative to thecylinder 104 by an external force provided by, e.g., wave power, by wayof example only in the present application. This reciprocating action ofthe piston/rod causes fluid to be drawn into the expanding cavity end ofthe cylinder 104, and expelled from the shrinking cavity end. For thepresent exemplary intended use as a high pressure sea water pumpingsystem, the inlet to the suction manifold 110 is filtered by a sandfilter 40 on the sea bed 41 followed by a fine strainer (not shown) toremove particulate matter that could cause excessive wear on the pistonpumps. Also, the low pressure and high pressure manifolds 106/108relieve excess pressure by porting fluid back to the suction manifold110 to provide a back flush action of the suction strainer, as does aseparate back flush valve 11 when opened momentarily.

As shown in FIG. 4, one end of the piston rod 102 is rotatably coupledto a first lever L1 while the non-rod end 104A of the cylinder 104 isrotatably coupled to a second lever L2. These levers L1/L2 arealternately moved together and then away from each other by an externalmechanical force (e.g., wave motion). This force causes the cylinderpiston rod 102 to alternately extend and contract, thus drawing fluidinto one piston cavity (either 104A or 104B) and expelling fluid out ofthe other piston cavity (either 104B or 104A). By way of example only,the fluid connections of this cylinder 104 are connected to the instantinvention configuration and control system schematic to providecontinuously flowing high pressure sea water to a target processrequiring such a continuous supply. For alternate use with a closedsystem hydraulic oil power generation system, the suction of thecylinder 104 would be from a sump (not shown), as opposed to a sandfilter 40 in the sea bed 41; the high pressure discharge would go to ahydraulic oil process, as opposed to a seawater process; the hydraulicprocess would discharge oil back to the sump, as opposed to dischargingsalt water back to sea as with a sea water process; and the two pressurecontrol/relief valves 12, 13, would drain the hydraulic oil back to thesump, as opposed to draining sea water to the suction manifold for backflushing the suction strainer as with the sea water process.

An apparatus for pumping sea water drawn from the sea to a processrequiring a continuous direct flow of high pressure sea water uses areciprocating pump powered by external mechanical forces. A powertake-off sub-system is a shaft that transfers mechanical power betweenmechanical systems. In another embodiment of the instant invention,power take-off is the transformation of power to fluid power. Anembodiment of the instant invention includes at least two power take-offsub-systems. e.g., a first power take-off sub-system and a second powertake-off sub-system. The first power take-off sub-system from thearticulated levers is, for example, a single rod end double-actinghydraulic cylinder pump. By itself, the double-acting hydraulic pumpproduces alternating fluid flow in and out of the fluid connections ateach end of the cylinder.

It should be noted that the useable volume in the rod end of thecylinder 104B actually forms an annular volume due to the presence ofthe rod 102. This can be most easily seen in FIGS. 9A-9C. Since theannular volume per unit length of piston 100 travel at the rod end ofthe cylinder 104B is less by the volume of the entrained piston rod 102than the volume per unit length of piston travel at the non-rod end ofthe cylinder 104A, there will be an excess of fluid expelled from thenon-rod end of the cylinder 104A equal to the volume of the entrainedpiston rod 102.

Four Fluid Functionalities

The fluid flow control system of the present invention 20 can beconfigured to provide four different fluid functionalities as describedin the following paragraphs. These configurations are realized throughappropriate positioning either locally or remotely using remoteactuators (not shown) to OPEN or SHUT the 2-way full-port (e.g., verylow flow resistance) ball valves 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 as shownin FIG. 4. Once these ball valves are positioned, they remain in thatposition indefinitely without further actuation required. Check valves21, 22, 23, 24, 25, 26 permit flow only in the direction shown by eachvalve, and only when there is a positive pressure differentialsufficient to cause that flow. Reverse flow is prohibited through thesevalves regardless of the pressure differential across them. Fluidhydraulic accumulator 31 stores excess fluid and maintains the lowpressure manifold 108 fluid pressure. Accumulator group 32 store excessfluid and maintain the high pressure manifold 106 fluid pressure.Pressure relief valve 12 restricts the low pressure manifold 108pressure to a specified maximum value by relieving fluid back to thesuction manifold 110 when the maximum specified value is reached for theopen loop water system (and back to the sump for a closed loop hydraulicoil system). Pressure relief valve 13 restricts the high pressuremanifold 106 pressure to a specified maximum value by relieving fluidback to the suction manifold 110 until the pressure is reducedsufficiently when the maximum specified value is reached for the openloop water system (or back to the sump for a closed loop hydraulic oilsystem). For the open water system, the relief water flow back to thesuction manifold 110 provides beneficial periodic back flushing of thesuction strainer 40. For additional suction strainer back flushing inall system configurations NORMALLY SHUT valve 11 is placed OPENmomentarily to provide flushing water from the high pressure manifold.

It should be noted that in FIGS. 5A-8B the “X” used in the diagramsindicates a “closed valve” while an “O” used in the diagrams indicatesan “open valve.”

Single-Acting Pumping Mode (SAPM): FIGS. 5A-5B

An embodiment of the instant invention of a reconfigurable fluid controland distribution system is, for example, a configuration to providesingle-acting pump delivery of high pressure sea water for deliverydirect flow to a reverse osmosis system for conversion to potable water.In this configuration, ball valves 1, 2, 5, 7 are placed in the OPENposition, while ball valves 3, 4, 6, 8, 9, 10, 11 are placed in the SHUTposition. Relief valves 12, 13 remain SHUT except for overpressureconditions where they relieve their respective manifold fluid back tothe suction manifold until the overpressure condition is corrected.

During the portion of the cycle where the external mechanical forcescause the two hinged levers to move apart and the piston rod 102 isextended (FIG. 5A), fluid that had been within the annular cavity 104Bat the rod end of the cylinder is expelled from that end of the cylinderat sufficient pressure to force the fluid through OPEN ball valve 1 andthrough check valve 24 into the high pressure manifold. Check valves 23,25 and SHUT valves 8, 9, 11 restrict the pumped high pressure fluid tothis path. During this same portion of the cycle, filtered and strainedfluid is drawn into the cavity at the non-rod end of the cylinder 104Afrom the suction manifold 110 through check valve 21 and OPEN ball valve2. Check valve 22 and SHUT valves 4, 6, 10, 11 restrict the suctionfluid to this path. During this high pressure pumping portion of thecycle the forces on the piston rod 102 are the greatest. By pumping fromthe rod end of the cylinder 104B, the greatest stress on the rod 102exists while it is in tension, thus the likelihood of rod 102 bendingand rod seal wear is minimized. As shown in FIG. 5A, full flow from therod-end 104B is delivered to the HP manifold 106, wherein one half ofthat full flow is delivered to the accumulators 32 and the other onehalf of the full flow is delivered to the target process. It should benoted that during this extension half-cycle, there is no flow lowpressure (LP) fluid movement in the LP manifold 108. The springaccumulators 33/34 also remain empty during this half-cycle.

During the portion of the cycle where the external mechanical forcescause the two hinged levers to move toward each other (FIG. 5B) and thepiston rod 102 to be pushed into the cylinder 104, fluid that was in thecavity 104B at the non-rod end of the cylinder is expelled from that endof the cylinder 104 at sufficient pressure to flow into the low pressuremanifold 108 and into the cavity at the rod end of the cylinder 104Bthrough OPEN ball valves 2, 7, 5, 1 and check valves 22, 23. Checkvalves 26, 21, 25, 24 (due to the higher pressure of the high pressuremanifold preventing a positive pressure differential across this lastcheck valve) and SHUT valves 3, 4, 6, 8 restrict the fluid transfer fromnon-rod end 104A to rod-end of the cylinder 104B to this path. Reliefvalves 12, 13 remain SHUT except for overpressure conditions where theyrelieve their respective manifold fluids back to the suction manifolduntil the overpressure condition is corrected. Thus, as shown in FIG.5B, there is no flow from the pump through the HP manifold 106 and onlythe one-half flow 111 is provided to the target process from theaccumulators 32 that was stored in those accumulators 32 in the previousextension one-half cycle (FIG. 5A). The spring accumulators 33/34 alsoremain empty during this half-cycle also.

As mentioned earlier, due to the annular volume of the rod-end chamber104B, there is an excess fluid (see excess fluid flow 109, in FIGS. 5Band 7A-7B) that is expelled from the non-rod chamber 104A. This excessfluid flows into the low pressure manifold 108. This repeated additionof fluid causes the pressure in the low pressure manifold 108 andaccumulator 31 to gradually increase until the maximum desired isreached. At this point, pressure relief valve 12 relieves fluid back tothe suction manifold 110 until the pressure is sufficiently reduced, andit ceases relieving. This periodic relief from the low pressure reliefvalve 12 provides the benefit of an automatic periodic back flush forthe suction screen 40.

Since the non-rod end of the cylinder 104B, which takes suction directlyfrom the sea, acts as a prime pump for the high pressure pumping rod endin this configuration, the cylinder 104 tends to supply fluid to thehigh pressure pump side with potentially less suction induced gascontent than if that side were to take direct sea suction.

Double-Acting Pumping Mode (DAPM): FIGS. 6A-6B

An alternate second embodiment of the instant invention of areconfigurable fluid control and distribution system is, for example, toreconfigure the system to provide double-acting pump delivery of highpressure sea water for delivery direct flow to a reverse osmosis systemfor conversion to potable water. In this configuration ball valves 1, 2,6, 8 are placed in the OPEN position, while ball valves 3, 4, 5, 7, 9,10, 11 are placed in the SHUT position, as are relief valves 12, 13except for overpressure conditions where they relieve their respectivemanifold fluids back to the suction manifold 110 until the overpressurecondition is corrected.

During the portion of the cycle where the external mechanical forcescause the two hinged levers to move apart and the piston rod 102 isextended (FIG. 6A), fluid that had been within the annular cavity at therod end of the cylinder 104B is expelled from that end of the cylinderat sufficient pressure to force the fluid through OPEN ball valve 1 andthrough check valve 24 into the high pressure manifold 106. Check valves22, 23, 25 and SHUT valves 4, 5, 7, 9, 10, 11 restrict the pumped highpressure fluid to this path. During this same portion of the cycle,filtered and strained fluid is drawn into the cavity at the non-rod endof the cylinder 104B from the suction manifold 110 through check valve21 and OPEN ball valve 2. Check valves 22, 23, and SHUT valves 4, 5, 7,9, 10, 11 restrict the suction fluid to this path. The springaccumulators 33/34 also remain empty during this half-cycle also.

During the portion of the cycle where the external mechanical forcescause the two hinged levers to move toward each other and the piston rodto be pushed into the cylinder 104 (FIG. 6B), fluid that was in thecavity at the non-rod end of the cylinder 104 is expelled from that endof the cylinder at sufficient pressure to flow into the high pressuremanifold through OPEN ball valves 2, 8 and check valve 22. Check valves21, 24, 26 and SHUT valves 4, 5, 7, 9, 10, 11 restrict the fluidtransfer from non-rod end 104A to rod end 104B of the cylinder to thispath. Relief valves 12, 13 remain SHUT except for overpressureconditions where they relieve their respective manifold fluid back tothe suction manifold 110 until the overpressure condition is corrected.The spring accumulators 33/34 also remain empty during this half-cyclealso.

In this double-acting high pressure pumping configuration, more thantwice the volume of high pressure fluid is supplied per external forcecycle than with the single-acting pump. The disadvantage is that highcompressive stresses are placed on the piston rod 102 during the non-rodend pumping phase. This can add to the likelihood of rod bending andincreased rod seal wear unless the rod is of a robust diameter. Inaddition, the low pressure manifold 108 is effectively isolated andthere is no differential volume induced automatic back flush of thesuction screen 40. This back flush must be accomplished by momentaryopening of the normally shut back flush valve 11. In addition, sinceboth sides 104A/104B of the cylinder take direct sea suction, theadvantages of a having a preliminary prime pump are lost.

Inactive Free Motion Mode (IFMM): FIGS. 7A-7B

An alternate third embodiment of the instant invention of areconfigurable fluid control and distribution system is to reconfigurethe system 20 to isolate the cylinder 104 from the rest of the pumpgroup if cylinders are working together in parallel, but stillpermitting the piston 100 to be cycled back and forth. This featurepermits increasing or decreasing the number of active cylinder pumps online to increase or decrease the flow rate of high pressure fluid asneeded without interruption of the targeted process. In thisconfiguration (FIG. 7A) ball valves 7, 9, 10 are placed in the OPENposition, while ball valves 1, 2, 3, 4, 5, 6, 8, 11 are placed in theSHUT position, as are relief valves 12, 13 except for overpressureconditions where they relieve their respective manifold fluid back tothe suction manifold until the overpressure condition is corrected.

It should be noted that the high pressure fluid in the HP manifold 106is being provided by the other pumps 20A that are operating in eitherthe SAPM or DAPM configurations.

During the entire external force cycle, fluid is pumped back and forthbetween the two internal cavities of the cylinder through open ballvalves 9, 10 with a minimum of external force required. While pumpingfrom the non-rod end cavity 104A to the rod-end cavity 104B (FIG. 7A),the excess fluid 109 due to the smaller volume of the rod end cavity104B due to the entrained piston rod 102, the low pressure manifold 108will supply the required extra fluid through OPEN ball valve 7. Duringthe other half cycle (FIG. 7B), while pumping from smaller rod-endcavity 104B to the larger non-rod end cavity 104A, the excess fluid 109will be pumped into the low pressure manifold 108 through OPEN ballvalve 7.

It should be noted that during the piston rod extension half cycle (FIG.7A), the low pressure manifold 108 provides extra fluid if maintained byother pumping cylinders, or the suction manifold 110 provides extrafluid if the LP manifold 108 is empty. Conversely, during the piston rodretraction half cycle (FIG. 7B), the fluid is pumped into the LPmanifold 108 and accumulator 31 for storage and retrieval during thenext half-cycle. Again, the spring accumulators 33/34 also remain emptyduring this half-cycle also.

Inactive Rigid Mode (IRM): FIGS. 8A-8B

An alternate fourth embodiment of the instant invention of areconfigurable fluid control and distribution system 20 is toreconfigure the system to isolate and rigidizing it by placing ahydraulic lock on the cylinder 104, to prevent displacement of thepiston 100. This locked piston configuration could be useful when, forexample, a bank of cylinders connected between two barges that areproviding power to generate high pressure sea water by wave action aremade rigid to make the two barges act as a single larger essentiallyrigid barge for ease of transport and other tasks. In thisconfiguration, ball valves 3, 4, 5, 7 are placed in the OPEN position,while ball valves 1, 2, 6, 8, 9, 10, 11 are placed in the SHUT position,as are relief valves 12, 13 except for overpressure conditions wherethey relieve their respective manifold fluid back to the suctionmanifold 110 until the overpressure condition is corrected.

During this evolution, the isolated pistons are connected at both endsto small spring accumulators 33/34 that act as stiff fluid springsconnected to the locked piston 100 to cushion and provide restoringforces against sudden external forces on the cylinder 104. Since theseaccumulators 33/34 are of use only when in the locked pistonconfiguration, their internal gas bladders must be precharged to ahigher pressure than normally encountered during system operation in theother the configurations. They will be in an empty fluid condition untilthis configuration is entered, with the internal gas charged bladderpushing against and keeping shut the internal spring-loaded fluidshutoff valve. If, after entering this configuration, large externalforces on the levers L1/L2 to which the piston rod 102 and the cylinder104 are connected are encountered causing the piston 100 to moveslightly, thus raising the pressure of the trapped fluid in one of thecylinder cavities to above the attached spring accumulator 33/34precharge pressure, a small amount of fluid from that cavity will bepumped into that spring accumulator raising its gas charge pressure asthe bladder is displaced slightly by the inflow fluid. At the same time,the cylinder cavity on the other side of the piston 100 will be suppliedthe required fluid to make up for the piston displacement from eitherits attached spring accumulator 33/34 if it contains fluid, or by thelow pressure manifold 108 through OPEN ball valves 3, 4, 5, 7 and checkvalves 25, 26 if the attached spring accumulator is emptied of itsfluid. Once there is sufficient fluid in the spring accumulatorconnected to that cavity, it will provide any necessary make up fluid tothe cavity. After each of these external force induced small pistonoscillations, the spring accumulator with the higher pressure due tofluid inflow will push some of that fluid back out when the disturbingforce is lessened, thus displacing the piston 100 in the oppositedirection while also decreasing that spring accumulator pressure due tothe fluid outflow. This outflow induced piston displacement will forcesome fluid from the opposite cavity into its attached springaccumulator, raising the pressure on that side. These pistondisplacements will continue until the fluid forces on each side of thepiston are equal. It should be noted that the spring accumulator/fluidpressure on the rod-end cavity will be higher than that of the non-rodend cavity when the piston forces are equal due to the smaller annularpiston area on the rod end. As each successive external forcedisturbance is applied to the cylinder 104, it will tend to cause thepiston 100 to displace in the opposite direction proportional to thedisturbing force. This will pump a corresponding amount of fluid intothe spring accumulator connected to that cavity and raise its pressure,while draining a corresponding amount of makeup fluid from the oppositespring accumulator and lower its pressure. This action will produce arestoring “spring” force on the piston 100 due to the differentialforces across the piston 100. This restoring force action will cushionthe isolated piston 100 in a manner similar to attached mechanicalsprings. The volume of the spring accumulator is inversely proportionalto the desired stiffness, as a smaller volume will have a greaterincrease in gas pressure, hence a greater resulting restoring force, fora given volume of fluid addition.

It should be noted that during startup in the IRM configuration, thespring accumulators 33/34 are initially empty. For small piston rodextension motions caused by large external forces, the LP manifold108/accumulator 31 will provide makeup fluid to the non-rod end of thecylinder 104A; or, if the LP manifold 108 is empty, the suction manifold108 will supply the makeup fluid. For small piston rod retractionmotions caused by large external forces, the LP manifold 108/accumulator31 will provide makeup fluid to the rod end of the cylinder 104B; or, ifthe LP manifold 108 is empty, the suction manifold 108 will supply themakeup fluid.

It should also be noted that for use only in this fourth mode, namely,the IRM, respective relief valves 14 and 15 are provided at the springaccumulators 33/34 for safety. These relief valves protect the system 20from experiencing unusually high pressures in the IRM configurationshould an unusually high force (e.g., large wave) try to extend orretract the locked piston. They relieve fluid from the affectedaccumulator side to drains D, rather than back to the suction manifold110 or the LP manifold 108 since the relief valves 14/15 are actuatedonly very occasionally and only with a small discharged quantity offluid, i.e., a small amount of fluid drained from either springaccumulator 33/34 results in a large pressure decrease back into thesafe region.

As can be appreciated, implementation of the IRM configuration requiresthat all pumps 20A for that group of pumps 20A be placed into the IRMconfiguration. Thus, unlike the IFMM where one or more pumps 20A may beplaced into that mode, the IRM configuration requires that all pumps 20Ain the group operate in the IRM configuration.

For the purpose of this specification, although reference has been madespecifically to salt water, one of ordinary skill in the art willrecognize that alternative liquids will provide the same functionality,including but not limited to fresh water, hydraulic oil, or any othertype of essentially incompressible fluid.

For the purpose of this specification, although reference has been madespecifically to a cylindrical single-ended piston pump, one of ordinaryskill in the art will recognize that this same function could beprovided by other equivalent piston configurations, including but notlimited to square or oval pistons and enclosing housings, double-endedpistons, or tandem connected piston pairs.

For the purpose of this specification, although reference has been madespecifically to local or remotely actuated two-way ball valves, one ofordinary skill in the art will recognize that this same functionalitycould be provided by other equivalent two-way valves, including but notlimited to spool or gate valves.

For the purpose of this specification, although reference has been madespecifically to bladder hydraulic accumulators, one of ordinary skill inthe art will recognize that this same functionality could be provided byother equivalent devices, including but not limited to pistons andpiston accumulators.

For the purpose of this specification, although reference has been madespecifically to ocean surface waves, one of ordinary skill in the artwill recognize that surface waves are present in other bodies of water,including but not limited to lakes and rivers.

For the purpose of this specification, although reference has been madespecifically to waves to provide the force to cause the reciprocatingpumping action, one of ordinary skill in the art will recognize thatthis power could be provided by any sort of primary power engine,including but not limited to water wheels, tidal turbines, electricmotors, or internal combustion engines.

Because numerous modifications and variations of the above describedinvention will occur to those of ordinary skill in the art, it is notdesired to limit the invention to the exact construction and operationillustrated and described. Accordingly, all suitable modifications andequivalents may that be resorted to fall within the scope of theinvention.

All such modifications and variations are intended to be included hereinwithin the scope of this disclosure.

While the invention has been described in detail and with reference tospecific examples thereof, it will be apparent to one skilled in the artthat various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

1.-12. (canceled)
 13. A method for permitting a plurality ofparallel-acting bi-directional pumps to be configured into a pluralityof operational modes, said method comprising: providing a plurality ofbi-directional pumps, each bi-directional pump having a singe piston andpiston rod that can translate within a cylinder in two oppositedirections, each piston separating said corresponding cylinder into twochambers, each piston displacing fluid located in each chamber when saidpiston is in motion due to external forces acting through each pistonrod and each cylinder; coupling each chamber, through a valve network,to a high pressure manifold, a low pressure manifold and a suctionmanifold, said high pressure manifold having an output for deliveringthe high pressure liquid to a target process and wherein said suctionmanifold provides a liquid input into said bi-directional pump system;and controlling said valve network so that each one of said plurality ofbi-directional pumps can be configured to deliver high pressure liquidfrom one of a single-acting pumping mode and a double-acting pumpingmode, said single-acting pumping mode delivering high pressure liquid tosaid target process during piston motion in one of said two oppositedirections and wherein said double-acting pumping mode delivering highpressure liquid to said target process during piston motion in both ofsaid two opposite directions.
 14. The method of claim 13 furthercomprising the step of isolating at least one bi-directional pump'scylinder from the cylinders of the remaining cylinders of said pluralityof bi-directional pumps, said step of isolating said at least onebi-directional pump's cylinder comprises configuring the valve networkof said at least one bi-directional pump to permit said piston of saidat least one bi-directional pump to be displaced in said two oppositedirections without contributing to said high pressure fluid output bysaid another bi-directional pump.
 15. The method of claim 14 furthercomprising the step of rigidizing all of said plurality ofbi-directional pumps for preventing the movement of the respectivepistons in each of said bi-directional pumps, said step of rigidizingall of said plurality of bi-directional pumps comprises configuring saidvalve network to prevent the displacement of said respective pistons insaid corresponding cylinders using trapped liquid.
 16. The method ofclaim 13 wherein one of said two opposite directions is defined as anextension wherein each piston is driven in a direction that includes thepiston rod and wherein maximum pressure in said high pressure manifoldis maintained by having at least one accumulator, coupled to said highpressure manifold, receive a portion of said high pressure flow whensaid piston is extended.
 17. The method of claim 16 further comprisingthe step of flushing of a suction filter that forms a portion of saidsuction manifold, said flushing step being accomplished by coupling atleast one relief valve in liquid communication with said high pressuremanifold, said at least one relief valve porting an excess liquid backto said suction manifold for accomplishing said flushing occurring whensaid maximum pressure in said high pressure manifold is exceeded. 18.The method of claim 13 wherein one of said chambers of each of saidplurality of bi-directional pumps comprises an annular volume due to thepresence of said piston rod therein and the other one of said chambersof each of said plurality of bi-directional pumps comprises acylindrical volume thereby resulting in an excess liquid being generatedby said cylindrical volume, and wherein said method further comprises atleast one accumulator in liquid communication with said low pressuremanifold, said at least one accumulator receiving said excess liquidfrom, and restoring said excess fluid to, said plurality ofbi-directional pumps during retraction and extension of said pistonstherein.
 19. The method of claim 16 further comprising the step offlushing of a suction filter that forms a portion of said suctionmanifold, said flushing step being accomplished by coupling at least onerelief valve in fluid communication with said low pressure manifold,said at least one relief valve porting an excess liquid back to saidsuction manifold for accomplishing said flushing occurring when saidmaximum pressure in said low pressure manifold is exceeded.
 20. Themethod of claim 13 wherein said piston rods and non-rod ends of saidcylinder of said plurality of bi-directional pumps are coupled torespective floating barges that are hinged together, and wherein wavemotion causes said floating barges to articulate about said hinges forpumping sea water as said liquid through said plurality ofbi-directional pumps.